Portable electronic devices continue to trend smaller while providing increased and improved functionality. Because of the limited space on the smaller devices, creative and sometimes less than ideal positioning of components occurs. For example, a microphone and a speaker may be positioned in close proximity of each other. This leads to a high degree of coupling from the speaker radiated signal to the microphone capsule. While this is not a big problem when the microphone is not being used to pick up a local talker, it is challenging for acoustic echo cancellers to spectrally subtract the speaker playback signal from the microphone signal that includes both the local talker and the speaker signal.
Also, because of the proximity of the speaker(s) to the microphones, the sound pressure level of the radiated signal from the speaker is often greater than that of the talker. This typically leads to a poor signal-to-noise ratio (SNR) and presents a formidable challenge for echo cancellers that can be exacerbated if the speaker to microphone path is non-linear.